The present invention relates to a method of forming a whiteware cast article and to compositions useful therein.
Slip casting is an ancient art. In the practice of this art, a particulate material is suspended in a slip medium to form a slip. The slip is poured into a mold typically made of plaster of paris. The slip medium is drawn out of the casting slip and a cast is left behind in the mold. The mold and cast are separated and the cast article is processed to give the final properties desired in the cast article. Slip casting is employed in the manufacture of whiteware including sanitary ware, such as sinks and toilets.
Pressure casting is a relatively recent modification of slip casting. In pressure casting, pressure is used to drive liquid out of the slip. Polymeric molds are commonly employed rather than the plaster molds useful in ordinary slip casting. For examples, see U.S. Pat. Nos. 4,464,485; 3,929,685; and 3,825,506.
While slip casting and pressure casting are both techniques well-known in the art, there are some problems associated with casting processes and the articles produced therefrom and attempts have been made to use various casting additives to correct some of these problems.
It would be desirable to have an additive for casting which would be of low molecular weight, would have good burnout characteristics, and would give higher casting rates without significantly adversely impacting the other casting properties of the slip. It would be further desirable to have such an additive which would maintain the green strength of the cast article.